Kielland Øystein Nordeide, Bech Claus, Einum Sigurd
Department of Biology Centre for Biodiversity Dynamics Norwegian University of Science and Technology, NTNU Trondheim Norway.
Department of Biology Norwegian University of Science and Technology, NTNU Trondheim Norway.
Ecol Evol. 2017 Nov 2;7(24):10567-10574. doi: 10.1002/ece3.3556. eCollection 2017 Dec.
Diversified bet-hedging (DBH) by production of within-genotype phenotypic variance may evolve to maximize fitness in stochastic environments. Bet-hedging is generally associated with parental effects, but phenotypic variation may also develop throughout life via developmental instability (DI). This opens for the possibility of a within-generation mechanism creating DBH during the lifetime of individuals. If so, DI could in fact be a plastic trait itself; if a fluctuating environment indicates uncertainty about future conditions, sensing such fluctuations could trigger DI as a DBH response. However, this possibility has received little empirical attention. Here, we test whether fluctuating environments may elicit such a response in the clonally reproducing crustacean . Specifically, we exposed genetically identical individuals to two environments of different thermal stability (stable vs. pronounced daily realistic temperature fluctuations) and tested for effects on DI in body mass and metabolic rate shortly before maturation. Furthermore, we also estimated the genetic variation in DI. Interestingly, fluctuating temperatures did not affect body mass, but metabolic rate decreased. We found no evidence for plasticity in DI in response to environmental fluctuations. The lack of plasticity was common to all genotypes, and for both traits studied. However, we found considerable evolvability for DI, which implies a general evolutionary potential for DBH under selection for increased phenotypic variance.
通过产生基因型内表型变异进行的多样化风险对冲（DBH）可能会进化，以在随机环境中最大化适应性。风险对冲通常与亲代效应相关，但表型变异也可能在整个生命过程中通过发育不稳定性（DI）产生。这为个体一生中产生DBH的代内机制提供了可能性。如果是这样，发育不稳定性实际上可能本身就是一种可塑性性状；如果波动的环境表明未来条件存在不确定性，感知这种波动可能会触发发育不稳定性作为一种风险对冲反应。然而，这种可能性很少受到实证关注。在这里，我们测试波动的环境是否会在克隆繁殖的甲壳类动物中引发这种反应。具体来说，我们将基因相同的个体置于两种热稳定性不同的环境中（稳定环境与明显的每日实际温度波动环境），并在成熟前不久测试对体重和代谢率方面发育不稳定性的影响。此外，我们还估计了发育不稳定性的遗传变异。有趣的是，温度波动并未影响体重，但代谢率下降了。我们没有发现发育不稳定性因环境波动而产生可塑性的证据。缺乏可塑性在所有基因型以及所研究的两个性状中都很常见。然而，我们发现发育不稳定性具有相当大的可进化性，这意味着在选择增加表型变异的情况下，风险对冲具有普遍的进化潜力。
